阅读说明：本技术 空化超声与紫外线联合进行牛奶灭菌的一体式装置 (Integrated device for performing milk sterilization by combining cavitation ultrasound and ultraviolet rays ) 是由 孙逊 陈颂英 玄晓旭 游炜彬 杨泽 王梦洁 于 2020-12-11 设计创作，主要内容包括：一种空化超声与紫外线联合进行牛奶灭菌的一体式装置,包括定子、转子、转轴、紫外线发射器和超声波换能器,定子的内壁上分布有超声换能器,定子两端面上均设置有紫外线发射器,定子两侧端面分别设置有排液口和进液口,转轴安装在定子中,转子处于定子中并固定安装在转轴上,转子上分布有叶片,叶片内带有空腔,叶片上在空腔相对的两侧设置有空化通孔。上述装置,通过高效耦合水力空化、超声空化与紫外线三种工艺,协同对牛奶进行处理,效果好,可放大性高,处理量大,可连续作业,成本低,不产生二次污染,在牛奶灭菌领域具有广阔的应用前景。(The utility model provides an integral type device that cavitation supersound and ultraviolet ray jointly carry out milk sterilization, includes stator, rotor, pivot, ultraviolet emitter and ultrasonic transducer, and it has ultrasonic transducer to distribute on the inner wall of stator, all is provided with ultraviolet emitter on the stator both ends face, and stator both sides terminal surface is provided with leakage fluid dram and inlet respectively, and the pivot is installed in the stator, and the rotor is in the stator and fixed mounting is in the pivot, and it has the blade to distribute on the rotor, has the cavity in the blade, is provided with the cavitation through-hole in the relative both sides of cavity on the blade. The device processes the milk by the efficient coupling of the three processes of the hydrodynamic cavitation, the ultrasonic cavitation and the ultraviolet rays, has good effect, high amplification, large treatment capacity, continuous operation, low cost and no secondary pollution, and has wide application prospect in the field of milk sterilization.)

1. The utility model provides an integral type device that cavitation supersound and ultraviolet ray jointly carry out milk sterilization which characterized by: the ultrasonic generator comprises a stator, a rotor, a rotating shaft, an ultraviolet emitter and an ultrasonic transducer, wherein the ultrasonic transducer is distributed on the inner wall of the stator, the ultraviolet emitter is arranged on the two end faces of the stator, a liquid discharge port and a liquid inlet are respectively arranged on the two side end faces of the stator, the rotating shaft is installed in the stator, the rotor is located in the stator and is fixedly installed in the rotating shaft, blades are distributed on the rotor, cavities are formed in the blades, and cavitation through holes are formed in the two opposite sides of the cavities on the blades.

2. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the inner diameter of the stator is 300-600 mm, the width of the stator is 200-500 mm, and the wall thickness is 15-30 mm; the length of the blade is 50-200 mm, the width is 30-60 mm, and the thickness is 10-30 mm.

3. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the ultrasonic transducers are distributed on the inner wall of the stator at equal intervals of 2-6 circles in each circle by 2-8 circles along the axial direction and the circumferential direction; the ultrasonic transducer is connected with an ultrasonic generator, the frequency of the ultrasonic generator is 40-75 kHz, and the single-machine power is 1500-3000W.

4. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the ultraviolet emitters are embedded on the end faces of the stators at equal angles in a circumferential array, 2-12 ultraviolet emitters are arranged on the end face of each side of the stator, and the power of a single machine is 15-100W; the number of the ultraviolet emitters on the end faces of the two sides of the stator is equal and the ultraviolet emitters correspond to one another.

5. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the liquid inlet and the liquid outlet are arranged diagonally to prevent short flow. The liquid inlet flow of the liquid inlet is 1.5-4.5 m³/h。

6. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the rotating speed of the rotating shaft is 4000-4500 r/min.

7. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the rotor is 2 ~ 6 in the epaxial axial equidistance distribution of pivot, the blade is 4 ~ 10 along circumference distribution at equidistant on the rotor.

8. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the axial line of the cavitation through hole is consistent with the rotation tangential direction of the rotor.

9. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the cavitation through hole is of a Venturi-shaped structure, an outlet and an inlet are respectively formed in two ends of the cavitation through hole, a throat part is formed in the middle of the cavitation through hole, the inner diameters of the outlet and the inlet are 1-6 mm, and the inner diameter of the throat part is 0.4-1 mm; the contraction angle is 35-50 degrees, and the expansion angle is 8-15 degrees.

10. The integrated device for milk sterilization by combining cavitated ultrasound and ultraviolet rays as claimed in claim 1, which is characterized in that: the cavitation through holes are arranged in 4-10 rows and 3-10 rows of rectangular arrays on each side of the blade, and the cavitation through holes on two sides of the cavity in the blade are aligned pairwise. The surface roughness Ra of the inner wall of the cavitation through hole is smaller than 1.6 mm.

Technical Field

The invention relates to a device for sterilizing milk, which combines hydrodynamic cavitation, ultrasonic cavitation and ultraviolet treatment technologies and belongs to the technical field of milk sterilization.

Background

Milk is one of the oldest natural beverages and is known as "white blood". The fresh milk is easily polluted by colibacillus, staphylococcus aureus, pseudomonas and fungi in the environment, as well as pathogenic bacteria and the like which are caused by animal bodies such as brucella, tubercle bacillus and the like and are suffered by human and livestock together. The fresh milk is not sufficiently sterilized, and is easy to cause the spread of zoonosis.

At present, two main ways are adopted for sterilizing milk: thermal sterilization and non-thermal sterilization.

The thermal sterilization mainly comprises the following steps:

1. low temperature long time pasteurization (LTLT): heating the milk to 62-65 ℃ after cooling the milk, keeping the temperature for 30 minutes, and performing heat preservation treatment at proper temperature and time by utilizing the characteristic of weak heat resistance of pathogens to completely kill the pathogens;

2. high temperature short time pasteurization (HTST): heating milk to 75-90 ℃, preserving heat for 15-16 seconds, and killing pathogenic bacteria;

3. ultra high temperature flash sterilization (UHT): setting the heating temperature of the milk to be 135-150 ℃ and the heating time to be 2-8 seconds, wherein pathogens are inactivated due to internal enzymes caused by high temperature and lose metabolism capability, so that the pathogens die;

the non-thermal sterilization mainly comprises the following steps:

4. ultrasonic sterilization: micro bubble nuclei are formed when high-intensity ultrasonic waves are transmitted in a liquid medium, and certain bacteria in the liquid are killed by high temperature and high pressure at the moment of adiabatic shrinkage and collapse due to the inside of the micro bubble nuclei;

5. chemical sterilization method: refers to a method in which chemicals directly act on microorganisms to kill them.

6. Ultra-high pressure sterilization: under the condition of normal temperature or lower temperature, the pressure is changed to kill the microbes such as bacteria.

The sterilization mode has the following disadvantages:

the LTLT method consumes longer time, and the milk product has short shelf life and needs to be refrigerated for storage;

the HTST method has residues of partial thermophilic bacteria, thermotolerant bacteria, spores and the like;

UHT method requires high temperature environment, which increases energy consumption, and high temperature causes lactose coking and damages taste;

4. ultrasonic sterilization is not thorough, more influencing factors are generated, and the treatment capacity is smaller;

5. chemical sterilization method, chemical residue can be generated after chemical treatment, which affects food safety;

6. the milk is subjected to ultra-high pressure sterilization, the milk needs to be pretreated, the pressure intensity needs to be strictly controlled, and the original taste, color, nutrition and the like of the milk are affected when the milk is too high or too low.

Therefore, how to solve the disadvantages of the existing milk sterilization methods is a technical problem which needs to be solved urgently in the field.

Cavitation refers to the process of formation, development and collapse of gas voids within a liquid or at a liquid-solid interface when the local pressure within the liquid drops. When the liquid pressure drops to or below the liquid saturation vapor pressure, a large number of cavitation bubbles are generated due to the vigorous vaporization of the liquid. The cavitation bubbles expand and grow along with the flow of the liquid. When the liquid pressure recovers, the cavitation bubbles are instantaneously collapsed to form micro jet and shock waves, and local high temperature and instantaneous high pressure are generated. The energy released by the cavitation phenomenon can also be utilized to realize the enhancement of the processes such as chemistry, physics and the like, and achieve the effects of efficiency enhancement, energy conservation, consumption reduction and the like. Therefore, the liquid material can be sterilized by the instantaneous high temperature and high pressure generated when the cavitation occurs.

However, the hydrodynamic cavitation treatment device on the market at present basically adopts the structure of the venturi tube and the cavitation nozzle to achieve the aim of cavitation, the structure has the problems of low cavitation efficiency, small treatment amount and low treatment efficiency, and the sterilization effect of the device directly used for milk is not ideal.

Disclosure of Invention

Aiming at the defects of the existing milk sterilization process, the invention provides an efficient, safe and reliable integrated device for performing milk sterilization by combining cavitation ultrasound and ultraviolet rays.

The invention discloses an integrated device for performing milk sterilization by combining cavitation ultrasound and ultraviolet rays, which adopts the following technical scheme:

the device, including stator, rotor, pivot, ultraviolet emitter and ultrasonic transducer, it has ultrasonic transducer to distribute on the inner wall of stator, all is provided with ultraviolet emitter on the stator both ends face, and stator both sides terminal surface is provided with leakage fluid dram and inlet respectively, and the pivot is installed in the stator, and the rotor is in the stator and fixed mounting is in the pivot, and it has the blade to distribute on the rotor, has the cavity in the blade, is provided with the cavitation through-hole in the relative both sides of cavity on the blade.

The inner diameter of the stator is 300-600 mm, the width of the stator is 200-500 mm, and the wall thickness is 15-30 mm.

The reaction temperature in the stator is 50-80 ℃ (the heating effect is from cavitation phenomenon).

Ultrasonic transducer is along axial and circumference with 2 ~ 8 per circle, totally 2 ~ 6 circles equidistant distribution on the stator inner wall. The ultrasonic transducer is connected with an ultrasonic generator, the frequency of the ultrasonic generator is 40-75 kHz, and the single-machine power is 1500-3000W.

The ultraviolet ray emitter is embedded on the stator terminal surface with the equal angle of circumference array, has 2 ~ 12 on the stator terminal surface of every side, and the unit power is 15 ~ 100W. The number of the ultraviolet emitters on the end faces of the two sides of the stator is equal and the ultraviolet emitters correspond to one another.

The liquid inlet and the liquid outlet are arranged diagonally to prevent short flow. The liquid inlet flow of the liquid inlet is 1.5-4.5 m³/h。

The rotating speed of the rotating shaft is 4000-4500 r/min.

The rotor is 2 ~ 6 at the epaxial axial equidistance of pivot distribution.

The blades are distributed on the rotor at equal intervals along the circumferential direction by 4-10 blades. The length of the blade is 50-200 mm, the width is 30-60 mm, and the thickness is 10-30 mm.

The axial line of the cavitation through hole is consistent with the rotation tangential direction of the rotor, but not consistent with the axial direction of the rotor.

The cavitation through hole is of a Venturi-shaped structure, an outlet and an inlet are respectively formed in two ends of the cavitation through hole, a throat part is formed in the middle of the cavitation through hole, the inner diameters of the outlet and the inlet are 1-6 mm, and the inner diameter of the throat part is 0.4-1 mm; the contraction angle is 35-50 degrees, and the expansion angle is 8-15 degrees. The cavitation through holes are arranged in 4-10 rows and 3-10 columns of rectangular arrays on each side of the blade. The cavitation through holes on two sides of the cavity in the blade are aligned in pairs (on the same axis). The surface roughness Ra of the inner wall of the cavitation through hole is smaller than 1.6 mm.

In order to ensure the formation of cavitation and efficiently realize the milk sterilization process, the structure and process parameters are obtained by actual sterilization experiments.

When the device is used for sterilizing pathogenic bacteria in milk, the milk is conveyed into the stator, the pathogenic bacteria in the milk are primarily killed under the irradiation of the ultraviolet emitter, and then the pathogenic bacteria are killed by hydrodynamic cavitation and ultrasonic cavitation, so that the sterilized milk is finally obtained.

The device adopts a rotating hydraulic cavitation technology, innovatively adopts the high-speed rotation of the rotating shaft to drive the rotor, so that the Venturi-shaped cavitation through holes on the rotor efficiently generate cavitation bubbles, and the cavitation bubbles collapse and release huge energy when the static pressure is recovered. This energy is manifested as local hot spots up to 5000K, high pressures of 1000bar, with powerful shock waves and high-speed microjets (150 m/s). In addition, under the extreme conditions described above, water molecules can be hydrolyzed to generate hydroxyl radicals, hydrogen peroxide radicals, and hydrogen peroxide, which have strong oxidizing properties. The ultrasonic wave and the ultraviolet treatment process are coupled at the same time of the action of the hydrodynamic cavitation effect, and the three are sterilized efficiently and synergistically, so that the energy generated during cavitation collapse is greatly enhanced, the generation of hydroxyl free radicals is promoted, and the sterilization effect is finally enhanced. The mechanical rotational kinetic energy required for cavitation constantly stirs the milk liquid, constantly refreshes the surface of the milk, and thus the ultraviolet rays can irradiate more milk liquid. Therefore, the combined use of the three components can obtain the sterilizing effect far higher than the sum of the sterilizing effect when the three components are used alone.

When milk enters the cavitator, ultraviolet rays can firstly have a certain killing effect on milk pathogenic bacteria, destroy and change the tissue structure of microorganisms, cause mutation of a nucleic acid structure and damage of functions, and enable organisms to lose the copying and propagating abilities, so that the aim of sterilization is fulfilled. The surface of the milk can be continuously renewed by mechanical rotation in the cavitator, and more milk can be irradiated by ultraviolet rays in a shorter time. Because of the low penetration of ultraviolet rays and the high turbidity of milk, ultraviolet treatment has only a limited effect on sterilization. Cavitation bubbles are generated in the cavitator through mechanical rotation, and the cavitation bubbles expand and grow along with the flowing of the liquid. When the liquid pressure recovers, the cavitation bubbles are instantaneously collapsed to form the phenomena of shock waves, micro jet and the like, and instantaneous local high temperature and instantaneous high pressure are generated. These shock waves, microjets, are highly destructive to the microorganisms, and the resulting momentary local high temperature and pressure effectively deactivate the microorganisms. Cavitation can produce hydroxyl radicals having an unpaired electron, which can remove electrons from other substances, with strong oxidizing properties. Microorganisms (including membrane surfaces, lipids and proteins) can be oxidized by hydroxyl groups through a chain reaction and are irreversibly damaged, the ultrasonic energy promotes the occurrence of hydrodynamic cavitation, and the cavitation realizes milk sterilization through the comprehensive action of mechanical, thermal and chemical effects.

The invention has the following characteristics:

1. the device provided by the invention combines the hydrodynamic cavitation, ultrasonic cavitation and ultraviolet technology to cooperate with milk sterilization, the efficiency is far higher (can be improved by more than 3-4 times) than that of a method of singly using hydrodynamic cavitation, ultrasonic cavitation or ultraviolet, the efficiency is high, the processing capacity of the method is large, and continuous operation can be realized;

2. the cavitation through holes in the rotor of the device are in a Venturi structure, and the Venturi-shaped cavitation through holes at the two ends of the blades are aligned in pairs so as to realize two continuous cavitation processes on the premise of not changing the number of the blades, so that the cavitation effect is multiplied, and the cavitation efficiency is far higher than that of the traditional device;

3. the cavity of the blade provides a high-flow-rate low-pressure generating surface for the cavitation process, so that the turbulence effect and the cavitation effect are enhanced;

4. the surface roughness Ra of the inner wall of the cavitation through hole of the rotor of the device is less than 1.6mm, so that the cavitation primary effect is enhanced, and the cavitation efficiency is improved;

5. the device adopts the symmetrical distribution of a plurality of rotors, each rotating disc is provided with an array Venturi hole, and the inner wall of the stator is provided with the ultrasonic transducer and the ultraviolet emitter, so that the treatment efficiency of the hydrodynamic cavitation is greatly improved compared with the traditional cavitator;

6. the ultrasonic transducer in the device can be made into any shape according to different containers, and the device is built in, so that the generated noise is small, and the energy attenuation is small;

7. the device has strong scalability, the sizes of the stator and the rotating disc type cavitation generator can be changed according to the treatment requirement, and the requirement of larger milk sterilization treatment capacity can be met by replacing a high-power device;

8. the device efficiently couples hydrodynamic cavitation, ultrasonic cavitation and ultraviolet technology, and the integrated equipment greatly simplifies the whole process flow;

9. in the running process of the device, the surfaces of the stator and the rotor are periodically cavitated and cleaned, so that the device has a self-cleaning function;

10. the device has the advantages of simple structure, strong adaptability, convenient operation, safety, reliability and convenient maintenance;

11. the device is not limited to milk sterilization, and is expected to have good treatment effect on other types of liquid-phase food sterilization;

12. the structure and technological parameters of the device are obtained by actual sterilization experiments;

13. the device has the advantages of high efficiency and low nutrition damage, and can completely replace the prior art.

Drawings

FIG. 1 is a schematic structural diagram of an integrated milk sterilization device coupled with hydrodynamic cavitation, ultrasonic cavitation and ultraviolet rays.

Fig. 2 is a schematic view of the distribution of ultraviolet emitters in the present invention.

Fig. 3 is a schematic cross-sectional view of a stator and rotor of the present invention.

Fig. 4 is a schematic view of a rotor structure according to the present invention.

FIG. 5 is an SEM micrograph of the inactivation effect of the device of the present invention on Escherichia coli, where a is before treatment and b is after treatment.

In the figure: 1. the device comprises a liquid outlet, 2 parts of a sealing cover, 3 parts of a sealing end cover, 4 parts of a rotating shaft, 5 parts of an angular contact ball bearing, 6 parts of a mechanical seal, 7 parts of an ultraviolet emitter, 8 parts of a stator end cover, 9 parts of a sealing gasket, 10 parts of a stator, 11 parts of an ultrasonic transducer, 12 parts of an ultrasonic generator, 13 parts of a cavitation through hole, 14 parts of a rotor, 15 parts of a liquid inlet, 16 parts of a wedge key, 17 parts of a cavity and 18 parts of blades.

Detailed Description

The invention discloses an integrated device for performing milk sterilization by combining cavitation ultrasound and ultraviolet rays, which comprises a stator 10, a rotor 14, a rotating shaft 4, an ultraviolet ray emitter 7 and an ultrasonic transducer 11, as shown in figure 1.

The stator 10 is a hollow sealing cylinder, two ends of the stator are connected with a stator end cover 8 through bolts, and a sealing gasket 9 is arranged at the joint, so that a sealed cavity is formed inside the stator 10. The inner part of the stator end cover 8 is provided with an angular contact ball bearing 5, the outer part of the stator end cover is provided with a sealing cover 2, the sealing cover 2 is connected with a sealing end cover 3, and a sealing ring 9 is arranged at the joint to form a sealing structure. The inner diameter of the stator 10 is 300-600 mm, the width of the stator is 200-500 mm, the wall thickness is 15-30 mm, and the ultrasonic transducer 11 is arranged on the inner wall of the stator. Each ultrasonic transducer 11 is connected to an ultrasonic generator 12. The ultrasonic transducer is embedded into the inner wall of the stator along the axial direction and the circumferential direction in an equidistant mode of 2-8 ultrasonic waves per circle and 2-6 ultrasonic waves in total. The number of the ultrasonic generators 12 is 1-4, the frequency is 40-75 kHz, and the single-machine power is 1500-3000W. After the ultrasonic wave is coupled, the energy generated when the cavitation bubble collapses can be greatly enhanced, the generation of hydroxyl free radicals is promoted, and the treatment effect is promoted. The end covers 8 of the stators on both sides are provided with ultraviolet emitters 7, see fig. 2. The ultraviolet emitters 7 are embedded in the stator end cover 8 in a circumferential array and equal-angle equal-division mode, each side of the ultraviolet emitters is 2-12, the single-machine power is 15-100W, and the ultraviolet emitters are fixed through a sealing structure. The ultraviolet emitters 7 on the two sides are equal in number and correspond to each other one by one, so that the same illumination intensity in different areas in the stator 10 can be ensured, and the ultraviolet reaction can be efficiently carried out.

Referring to fig. 2, the lower part of the left end cover of the stator is provided with a liquid outlet 1, and the upper part of the right end cover is provided with a liquid inlet 15. The liquid inlet 15 and the liquid outlet 1 are arranged diagonally to prevent short flow. The liquid inlet 15 and the water outlet 1 are respectively connected with a control valve for controlling the flow. The liquid inlet flow of the liquid inlet is 1.5-4.5 m³H is used as the reference value. Because the cavitation collapse continuously generates heat, the reaction temperature in the stator is 50-85 ℃.

The rotating shaft 4 is installed in the stator 10 through an angular contact ball bearing 5, one end of the rotating shaft extends out of the stator 10 and is sequentially connected with a speed increaser and a motor through a coupler, and the rotor 14 is driven to rotate in the stator 10. The joint of the rotating shaft 4 and the stator 10 is provided with a mechanical seal 6, and the mechanical seal 6 is arranged outside the stator end cover 8 and inside the sealing cover 2 to ensure the sealing performance of the device. The rotating speed of the rotating shaft 4 is 4000-4500 r/min. The rotor 14 is located in the cavity of the stator 10 and is fixedly mounted on the shaft 4 by means of a wedge key 16.

2-6 rotors 14 are axially and equidistantly distributed on the rotating shaft 4, and the rotors 14 are in a multi-blade impeller structure, as shown in fig. 3 and 4. The blades 18 are of a hollow trapezoid structure with a cavity 17, and 4-10 blades are distributed on the rotor 14 at equal intervals along the circumferential direction. The cavity 17 provides a high-flow-rate low-pressure generating surface for the cavitation process, enhances the turbulent flow effect and enhances the cavitation effect. The length of the blade 18 is 50-200 mm, the width is 30-60 mm, and the thickness is 10-30 mm. The blades 18 are provided with cavitation through holes 13 on two opposite sides of the cavity 17, and the axes of the cavitation through holes 13 are consistent with the rotation tangential direction of the rotor, but not consistent with the axial direction of the rotor. The cavitation through hole 13 is of a Venturi-shaped structure, an outlet and an inlet are respectively arranged at two ends, a throat part is arranged in the middle of the cavitation through hole, the inner diameters of the outlet and the inlet are 1-6 mm, and the inner diameter of the central throat part is 0.4-1 mm; the contraction angle is 35-50 degrees, and the expansion angle is 8-15 degrees. The cavitation through holes 13 are arranged in a rectangular array of 4-10 rows and 3-10 columns on each side of the blade, and are beneficial to generation and collapse of cavitation bubbles. Each pair of venturi-shaped cavitation through holes 13 on both sides of the blade 18 are aligned two by two (on the same axis). When the rotor rotates at a high speed, fluid enters from the large end of the cavitation through hole 13 on one side, flows through the throat to generate cavitation, and then flows out from the small end; then the fluid enters into the cavitation through hole on the other side to induce the cavitation phenomenon again. Therefore, the structure can realize two times of continuous cavitation processes on the premise of not changing the number of the blades, and the cavitation effect is multiplied. The surface roughness Ra of the inner wall of the cavitation through hole 13 is less than 1.6mm, so that the cavitation initial effect is enhanced, and further the cavitation efficiency is improved.

The structure and the parameters are obtained through an actual sterilization experiment according to the milk sterilization characteristics, and the optimal matching effect of the treatment effect is achieved.

The process of sterilizing milk using the above-described apparatus of the present invention is as follows.

The milk is conveyed into the stator 10 from the liquid inlet 15 through the pressure pump, and the flow rate is 1.5-4.5 m³H is used as the reference value. The motor drives the rotating shaft 4 and the rotor 14 on the rotating shaft to rotate at a high speed, so that the cavitation through holes 13 on the blades 18 shear fluid at a high speed, the local static pressure of milk is lower than the saturated vapor pressure, and the hydrodynamic cavitation phenomenon is induced. Meanwhile, the external ultrasonic generator 12 converts electricity into a high-frequency alternating current signal matched with the ultrasonic transducer 11, and transmits the high-frequency alternating current signal to the ultrasonic transducer 11 embedded on the inner wall of the stator 10, and the ultrasonic transducer converts electric energy into sound energy to generate high-frequency ultrasonic waves. The ultrasonic wave acts on the fluid to induce the ultrasonic cavitation phenomenon, thereby greatly increasing the number of cavitation bubbles generated by the hydraulic cavitation, improving the collapse intensity of the cavitation bubbles and improving the treatment efficiency of the device. The extremely high temperature and high pressure condition generated by the cavitation phenomenon greatly enhances the sterilization effect. The mechanical rotation motion continuously stirs the milk, so that the surface of the milk is continuously updated, and more milk can be irradiated by the ultraviolet rays. The coupling of the three treatment processes greatly enhances the treatment effect and better achieves the aim of sterilization. The treated milk flows out through the liquid outlet 1 and then enters the liquid inlet 15 for circular treatment until a satisfactory sterilization result is obtained.

According to the invention, through milk sterilization experiments, under the optimal working condition and the structure (parameters are that the inner diameter of a stator is 400mm, the width of the stator is 340mm, the wall thickness is 30mm, the length of a blade is 130mm, the width is 60mm, the thickness is 30mm, the inner diameters of an outlet and an inlet of a Venturi hole are 6mm, the inner diameter of a central throat part is 0.7mm, a contraction angle is 45 degrees, an expansion angle is 11 degrees, the Venturi holes on the blade are arranged in a 5 x 4 rectangular array, 4 ultrasonic transducers are arranged in each row and 6 rows in total, 2 ultrasonic generators are provided, the single-machine power is 2000W, the single side of each ultraviolet emitter is 7, and the single-machine power is 45W), the following conclusion is obtained:

at a speed of 4500rpm, the flow rate was 2.6m³The sterilization can be realized for 60L of original milk respectively inoculated with typical pathogenic bacteria such as Escherichia coli, staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Bacillus cereus and the like within 5 minutes under the conditions that the ultrasonic frequency is 40kHz and the reaction temperature is 75 ℃ (the sterilization rate is 100 percent and the logarithmic reduction is more than 6 percent). FIG. 5 shows the inactivation of Escherichia coli by the device of the present invention under SEM electron microscope. Left panel a is a full, intact E.coli strain prior to treatment. After the treatment (right panel b), the surface is rough, folds are increased, cell walls are destroyed, and intracellular substances flow out; some bacteria are even directly divided into two parts, and the structure of the bacteria is completely destroyed.

The nutritional components of the milk before and after sterilization were analyzed to verify the destructive effect of the device on the nutritional components of the milk, and the results are shown in the following table:

from the above analysis of the milk nutrient composition list before and after sterilization, the destruction degree of minerals, milk fat, milk protein and vitamins by the device is found to be slightly lower than that of the traditional HTST sterilization method. Therefore, the device has the advantages of high efficiency and low nutrition damage.